The traditional basis for nonoperative treatment of clubfoot has been the stretching of soft tissues to allow relatively more normal hind foot bone (anlagen) positions. We have developed reliable techniques to create from MRI quantitative models of the shapes and relative positions of the anlagen, and to document changes in shape and relative position over time using serial MRI. The models have high interobserver reliability. Our preliminary observations suggest an additional and distinct mechanism from the traditional one relating to ligament stretching and relative anlagen positions: with manipulation and corrective casting there is immediate deformation of the soft cartilage anlagen themselves with "loss" of material in some locations and "addition" of material in others. This deformation results in a more normal shape. During the days the foot is maintained in the cast, the anlagen adapts to this new shape, which it maintains when the cast is removed. Over the course of repeated manipulations and castings, it appears the deformation results in a progressively more normal shape. If confirmed, these observations could provide new guidelines for the frequency of manipulation and casting and the timing of their cessation, and perhaps a higher rate of success. They will also change the way we think about early correction of deformities of these anlagen. We have two specific aims: 1) Enhance the processing of the digital MR images used to quantify the shapes of the anlagen and the correction of their relative positions; and 2) Quantify the changes induced by the Ponseti method in the shapes of the anlagen and their relative positions. To achieve these aims, MRI data collection will occur during the course of treatment by Dr. Pirani using the Ponseti method of manipulation and corrective casting technique. Ten infant subjects with congenital idiopathic unilateral clubfeet that have not had any previous treatment will be included. We view this proposal as the beginning of a longer term strategy to improve the nonoperative treatment of clubfoot and to explore the mechanisms by which these cartilage anlagen develop. [unreadable] [unreadable] [unreadable]